Deleting/Removing TK objects

Hi,

I would like to know how to remove/delete TK objects/widgets.

For example:
$frame{x} = $mw->Button( ......);
$frame{y} = $mw->Entry(.......);
.
.
.

How do I delete the Button?
How do I delete Entry?

Basically, I am writing an app; the mainwindow is filled with button menus.
If I click on any of the buttons, it will clear (either delete or hide) the
window of buttons and populate the window with other stuffs.
Once I am done, it will clear it and go back to mainwindow with buttons.

Dan